Texas Instruments LF298MX/NOPB

Overview

LF298MX/NOPB from Texas Instruments is a monolithic BI-FET sample-and-hold IC operating as a unity-gain follower with 0.002% typical DC gain accuracy, ≤10 µs acquisition time to 0.1%, and 0.5 mV typical hold step at 0.01 µF hold capacitance. It supports ±5 V to ±18 V dual supplies and interfaces directly with TTL/CMOS logic for precision data acquisition in instrumentation and test systems.

For engineers reviewing the LF298MX/NOPB datasheet, LF298MX/NOPB pinout, LF298MX/NOPB application, or LF298MX/NOPB equivalent, this page delivers verified electrical parameters, SOIC-14 package mapping, functional mode behavior, real-world application constraints, and validated alternative options - all grounded in TI's SNOSBI3C revision C datasheet.

Technical Context

The LF298MX/NOPB implements a bipolar input stage combined with P-channel JFET output devices to achieve low offset voltage (≤3 mV typ), wide bandwidth (>1 MHz usable in op-amp feedback loops), and ultralow hold capacitor leakage (30–100 pA at 25°C). Its differential logic interface uses a 1.4 V threshold referenced to LOGIC REFERENCE, enabling direct TTL/PMOS/CMOS compatibility without level-shifting.

Functional operation is strictly binary: sample mode (LOGIC > LOGIC REFERENCE by ≥1.4 V) enables output tracking of input via hold capacitor charging/discharging; hold mode (LOGIC < LOGIC REFERENCE by ≥1.4 V) disconnects input and freezes output voltage. Input impedance remains stable at 10¹⁰ Ω in both modes, and feedthrough attenuation exceeds 86 dB at 1 kHz.

Key Specifications

Pinout & Package

LF298MX/NOPB is housed in a 14-pin SOIC (D package) with nominal body size 8.65 mm × 3.91 mm. Pin 1 is marked with a dot; pin numbering follows standard SOIC convention (counterclockwise from top-left corner).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar sample-and-hold applications.

Compared with LF298MX/NOPB, LF398N/NOPB offers simpler packaging but sacrifices DC accuracy and thermal range, while LF198N/NOPB delivers superior specs in a non-SOIC form factor - making LF298MX/NOPB the optimal balance of performance, package compatibility, and commercial temperature support.

Availability

LF298MX/NOPB is available at Aetrix Electronics and suitable for precision instrumentation, automated test equipment, and high-speed data acquisition systems requiring stable component supply, long-term lifecycle continuity, and traceable sourcing.

Supply support for LF298MX/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of heritage in precision linear ICs and data conversion solutions.

The LFx98x product line was designed specifically for high-fidelity sample-and-hold applications in test & measurement, industrial control, and medical instrumentation - emphasizing DC accuracy, low droop, and logic interoperability.

FAQ

What is the maximum recommended hold capacitor value for LF298MX/NOPB?

The LF298MX/NOPB datasheet does not specify an absolute maximum hold capacitor value, but practical limits arise from acquisition time and droop trade-offs. With Ch = 0.01 µF, acquisition time is ≤10 µs; increasing to 1 µF reduces droop to ~5 mV/min but extends acquisition to ~20 µs. Capacitors >1 µF risk excessive charging current and thermal stress - TI recommends staying within 0.001–0.1 µF for most high-speed applications. The LF298MX/NOPB internal 300-Ω series resistor governs this behavior.

Does LF298MX/NOPB support single-supply operation?

No, LF298MX/NOPB requires dual ±V_S supplies per its Absolute Maximum Ratings and Recommended Operating Conditions. It is specified for ±5 V to ±18 V operation only. Attempting single-supply use (e.g., 0 V and +15 V) violates the input voltage range constraint (–V_S + 3.5 V ≤ V_IN ≤ +V_S – 3.5 V) and risks latch-up or permanent damage. For single-supply sample-and-hold, consider purpose-built alternatives like the THS-HOLD series.

How does logic rise time affect hold step in LF298MX/NOPB?

TI specifies a minimum dV/dt of 1.0 V/µs for the LOGIC input signal. Slower edges increase hold step due to timing uncertainty between analog sampling and logic transition. A 100-ns delay in logic edge arrival relative to ideal timing can induce up to 60 mV error on a 0.6 V/µs input slope. The LF298MX/NOPB's differential logic architecture helps reject common-mode noise, but edge rate remains critical - use fast logic drivers or small-series resistors to preserve slew rate into the LOGIC pin.

Can LF298MX/NOPB be used inside the feedback loop of an op-amp?

Yes - the LF298MX/NOPB's wide bandwidth and stable phase margin allow inclusion inside the feedback loop of 1-MHz operational amplifiers without stability issues. This is explicitly confirmed in TI's SNOSBI3C datasheet Section 8.1. The key enablers are its bipolar input stage (for bandwidth) and consistent input impedance in both sample and hold modes. When used this way, the LF298MX/NOPB acts as a programmable gain block or adaptive filter element, not just a passive hold device.

What capacitor dielectric types are recommended for Ch in LF298MX/NOPB?

TI recommends polystyrene, polypropylene, or C0G/NPO ceramic capacitors for Ch due to low dielectric absorption (<0.01%). Mylar and standard ceramics exhibit >1% hysteresis, causing voltage sag after hold - degrading accuracy in precision applications. Polypropylene extends max ambient temperature to 100°C vs. 85°C for polystyrene. Avoid electrolytics and high-K ceramics (X7R, Y5V). For 0.01 µF, a 5% tolerance polypropylene film capacitor is optimal for balancing cost, size, and performance in the LF298MX/NOPB.